Question: Rewrite ${\dfrac{9^{-5}}{9^{-10}}}$ in the form ${9^n}$.
Answer: ${ \dfrac{9^{-5}}{9^{-10}} = 9^{-5-(-10)}} $ ${ \hphantom{\dfrac{9^{-5}}{9^{-10}}} = 9^{5}} $